1. Field of the Invention
The present invention relates to a power saving method and apparatus for use in a mesh network. More particularly, the present invention relates to a power saving method and apparatus for saving power by reducing the number of changes between active mode and sleep mode using multiple channels.
2. Description of the Related Art
A conventional power saving method will be described with reference to FIG. 1. FIG. 1 illustrates a transmission opportunity (TXOP) allocation based on a TXOP media access plan (MAP) in a conventional wireless local area network (WLAN).
The TXOP between node A and node B during interval t1 is TXOPi, the TXOP between the node A and node C during interval t2 is TXOPj, and the TXOP between node C and node D during interval t3 is TXOPk.
In FIG. 1, a change between active mode and sleep mode frequently occurs in nodes C and D. Specifically, node C is in sleep mode during interval t1 and is in active mode during interval t2. During interval t3 and the remaining service interval (SI), node C is in sleep mode. Node D is in sleep mode during intervals t1 and t2 and is in the active mode during interval t3. During other intervals, node D is in sleep mode. Since a change between active mode and sleep mode frequently occurs in nodes C and D, node power is quickly consumed.
The conventional technology has a complex mechanism because all TXOPs are allocated within a single channel. Because resources are shared in the single channel in the conventional technology, each node cannot use resources other than its own TXOP.
On the other hand, a mesh network has a multipoint-to-multipoint structure, which is different from the Institute of Electrical and Electronics Engineers (IEEE) 802.11 structure. When the mesh network with the multipoint-to-multipoint structure uses the conventional technology, a TXOP allocation mechanism is more complex and the resource use rate is more degraded. Further, when the active and sleep modes of each node are repeated within an SI in the mesh network as illustrated in FIG. 1, the lifetime is shortened due to increased power consumption.
Accordingly, there is a need for an improved power saving method and apparatus that can save power by reducing changes between active mode and sleep mode using multiple channels.